More from WebMD

Feb. 3, 2009 -- People on dialysis who live at higher altitudes have a significantly lower rate of death than those who live near sea level, a new study shows.

Wolfgang C. Winkelmayer, MD, ScD, of Brigham and Women's Hospital and Harvard Medical School, analyzed the effects of increased altitude on the rate of death for patients on chronic dialysis. The study's findings appear in the Feb. 4 issue of the Journal of the American Medical Association.

Researchers identified 804,812 people with end-stage renal disease who started dialysis between 1995 and 2004. About 40% of the patients lived at altitudes of 250 feet or less, and 54.4% resided at elevations between 250 feet and 1,999 feet.

Only 1.9% of dialysis patients analyzed lived between 4,000 feet and 5,999 feet, and 0.4% lived higher than 6,000 feet.

Compared with people who lived at or near sea level, the rate of death was reduced by 3% for patients living at up to 1,999 feet and by 7% for those living between 2,000 and 3,999 feet.

The death rate was reduced by 12% for people living at elevations between 4,000 and 5,999 feet and by 15% for those living higher than 6,000 feet.

The five-year survival rate was 34% for people living at or near sea level, but 42.7% for those residing at altitudes higher than 6,000 feet.

"We found a graded reduction in mortality from any cause in ESRD (end-stage renal disease) patients residing at greater altitude, a finding that was not explained by differences in observed patient characteristics," the researchers say.

They conclude that factors related to lower oxygen levels at high altitudes confer "protective effects" on people with renal disease.

The article discloses that Winkelmayer and fellow researcher M. Alan Brookhart, PhD, have received grant support from pharmaceutical companies.